Maryland Rep. Dutch Ruppersberger was part of a conference call with President Barack Obama Thursday night and the president said he has not made a decision on what he's going to do with Syria.

"The president made it clear that the mission was to hold Assad accountable for the use of chemical weapons," he said. "He also has not made a decision on what he's going to do or when he's going to do it but he said it will be in the best interest of the United States."

Ruppersberger (D-MD), a member of the House Select Committee on Intelligence, said the conference call involved members of Congress and Obama's national security team and lasted about 90 minutes.

The purpose of the call was to explain why they believe Bashar Assad's government was the culprit in a suspected chemical attack last week. Lawmakers from both parties have been pressing Obama to provide a legal rationale for military action and specify objectives, as well as to lay out a firm case linking Assad to the attack.

A number of lawmakers raised questions in the briefing about how the administration would finance a military operation as the Pentagon is grappling with automatic spending cuts and reduced budgets.

"Even Russia and China have agreed in the past that they can't use chemical weapons and there has to be some accountability for that," he said. "What that is, is being developed right now."

Ruppersberger said that also means educating Congress and the American people as to what is happening in Syria.

"Part of that would be declassifying some information to present to the American public," he said.

Assad, who has denied using chemical weapons, vowed his country "will defend itself against any aggression."

Some of the U.N. chemical weapons experts will travel directly from Syria on Saturday to different laboratories around Europe to deliver "an extensive amount of material" gathered, U.N. spokesman Farhan Haq said. While the mandate of the U.N. team is to determine whether chemical agents were used in the attack, not who was responsible, Haq suggested the evidence - which includes biological samples and witness interviews - might give an indication of who deployed gases.

Obama and other top officials have not revealed definitive evidence to back claims that Assad used chemical weapons on Syrians. U.S. officials say the intelligence assessments are no "slam dunk," with questions remaining about who actually controls some of Syria's chemical weapons stores and doubts about whether Assad himself ordered the strike.